The Basque derby is the name of the football local derby between Real Sociedad and Athletic Bilbao. It embodies the inter-city rivalry between Bilbao and Donostia-San Sebastián, respectively the capitals of the neighbouring provinces of Biscay (Bizkaia) and Gipuzkoa in the Basque Country region of Spain. It is also occasionally referred to as the AP-8 derby, referring to the name of the highway which connects the cities.

Athletic Club, commonly known as just Athletic domestically and often as Athletic Bilbao abroad, is a professional football club based in the city of Bilbao in the Basque Country, Spain. They are known as Los Leones because their stadium was built near a church called San Mamés, which was named after Saint Mammes, an early Christian thrown to the lions by the Romans. Mammes pacified the lions and was later made a saint. The team plays its home matches at the San Mamés Stadium. Its home colours are red and white-striped shirts with black shorts.